Answer:
13.5
Explanation:
Potassium hydroxide fully ionizes when dissolved in water according to the following equation:
K
O
H
→
K
+
+
O
H
−
Now, let's find the relationship between
K
O
H
and
O
H
−
1
:
1
ratio
⇒
[
K
O
H
]
=
[
O
H
−
]
=
6.7
×
10
−
3
M
In any aqueous solution,
[
H
3
O
+
]
and
[
O
H
−
]
must satisfy the following condition:
[
H
3
O
+
]
[
O
H
−
]
=
K
w
[
H
3
O
+
]
=
K
w
[
O
H
−
]
[
H
3
O
+
]
=
1.0
×
10
−
14
6.7
×
10
−
3
[
H
3
O
+
]
=
1.5
×
10
−
12
M
Now, after finding the concentration of the hydronium ion, the pH of the solution is determined:
p
H
=
−
log
[
H
3
O
+
]
p
H
=
−
log
[
1.5
×
10
−
12
]
p
H
=
11.83
Other Method
Find the pOH using the concentration of the hydroxide ion, then use the formula
p
H
+
P
O
H
=
14
to find the pH.
